Oct4+ stem/progenitor swine lung epithelial cells are targets for influenza virus replication

Tissue Tropisms of Avian Influenza A Viruses Affect Their Spillovers from Wild Birds to Pigs

Wild aquatic birds maintain a large, genetically diverse pool of influenza A viruses (IAVs), which can be transmitted to lower mammals and, ultimately, humans. Through phenotypic analyses of viral replication efficiency, only a small set of avian IAVs were found to replicate well in epithelial cells of the swine upper respiratory tract, and these viruses were shown to infect and cause virus shedding in pigs. Such a phenotypic trait of the viral replication efficiency appears to emerge randomly and is distributed among IAVs across multiple avian species and geographic and temporal orders. It is not determined by receptor binding preference but is determined by other markers across genomic segments, such as those in the ribonucleoprotein complex. This study demonstrates that phenotypic variants of viral replication efficiency exist among avian IAVs but that only a few of these may result in viral shedding in pigs upon infection, providing opportunities for these viruses to become adapted to pigs, thus posing a higher potential risk for creating novel variants or detrimental reassortants within pig populations.IMPORTANCE Swine serve as a mixing vessel for generating pandemic strains of human influenza virus. All hemagglutinin subtypes of IAVs can infect swine; however, only sporadic cases of infection with avian IAVs are reported in domestic swine. The molecular mechanisms affecting the ability of avian IAVs to infect swine are still not fully understood. From the findings of phenotypic analyses, this study suggests that the tissue tropisms (i.e., in swine upper respiratory tracts) of avian IAVs affect their spillovers from wild birds to pigs. It was found that this phenotype is determined not by receptor binding preference but is determined by other markers across genomic segments, such as those in the ribonucleoprotein complex. In addition, our results show that such a phenotypic trait was sporadically and randomly distributed among IAVs across multiple avian species and geographic and temporal orders. This study suggests an efficient way for assessment of the risk posed by avian IAVs, such as in evaluating their potentials to be transmitted from birds to pigs.

Consecutive Hypoxia Decreases Expression of NOTCH3, HEY1, CC10, and FOXJ1 via NKX2-1 Downregulation and Intermittent Hypoxia-Reoxygenation Increases Expression of BMP4, NOTCH1, MKI67, OCT4, and MUC5AC via HIF1A Upregulation in Human Bronchial Epithelial Cells

Previous studies have shown that the experimental models of hypoxia-reoxygenation (H/R) mimics the physiological conditions of ischemia-reperfusion and induce oxidative stress and injury in various types of organs, tissues, and cells, both in vivo and in vitro, including human lung adenocarcinoma epithelial cells. Nonetheless, it had not been reported whether H/R affected proliferation, apoptosis, and expression of stem/progenitor cell markers in the bronchial epithelial cells. In this study, we investigated differential effects of consecutive hypoxia and intermittent 24/24-h cycles of H/R on human bronchial epithelial (HBE) cells derived from the same-race and age-matched healthy subjects (i.e., NHBE) and subjects with chronic obstructive pulmonary disease (COPD) (i.e., DHBE). To analyze gene/protein expression during differentiation, both the NHBE and DHBE cells at the 2nd passage were cultured at the air-liquid interface (ALI) in the differentiation medium under normoxia for 3 days, followed by either culturing under hypoxia (1% O₂) for consecutively 9 days and then returning to normoxia for another 9 days, or culturing under 24/24-h cycles of H/R (i.e., 24 h of 1% O₂ followed by 24 h of 21% O₂, repetitively) for 18 days in total, so that all differentiating HBE cells were exposed to hypoxia for a total of 9 days. In both the normal and diseased HBE cells, intermittent H/R significantly increased HIF1A, BMP4, NOTCH1, MKI67, OCT4, and MUC5AC expression, while consecutive hypoxia significantly decreased NKX2-1, NOTCH3, HEY1, CC10, and FOXJ1 expression. Inhibition of HIF1A or NKX2-1 expression by siRNA transfection respectively decreased BMP4/NOTCH1/MKI67/OCT4/MUC5AC and NOTCH3/HEY1/CC10/FOXJ1 expression in the HBE cells cultured under intermittent H/R to the same levels under normoxia. Overexpression of NKX2-1 via cDNA transfection caused more than 2.8-fold increases in NOTCH3, HEY1, and FOXJ1 mRNA levels in the HBE cells cultured under consecutive hypoxia compared to the levels under normoxia. Taken together, our results show for the first time that consecutive hypoxia decreased expression of the co-regulated gene module NOTCH3/HEY1/CC10 and the ciliogenesis-inducing transcription factor gene FOXJ1 via NKX2-1 mRNA downregulation, while intermittent H/R increased expression of the co-regulated gene module BMP4/NOTCH1/MKI67/OCT4 and the predominant airway mucin gene MUC5AC via HIF1A mRNA upregulation.

Characterization of Influenza A Virus Infection in Mouse Pulmonary Stem/Progenitor Cells

The pulmonary stem/progenitor cells, which could be differentiated into downstream cells to repair tissue damage caused by influenza A virus, have also been shown to be the target cells of influenza virus infection. In this study, mouse pulmonary stem/progenitor cells (mPSCs) with capability to differentiate into type I or type II alveolar cells were used as an in vitro cell model to characterize replication and pathogenic effects of influenza viruses in PSCs. First, mPSCs and its immortalized cell line mPSCs^Oct4+ were shown to be susceptible to PR8, seasonal H1N1, 2009 pandemic H1N1, and H7N9 influenza viruses and can generate infectious virus particles, although with a lower virus titer, which could be attributed by the reduced vRNA replication and nucleoprotein (NP) aggregation in the cytoplasm. Nevertheless, a significant increase of interleukin (IL)-6 and interferon (IFN)-γ at 12 h and IFN-β at 24 h post infection in mPSCs implicates that mPSCs might function as a sensor to modulate immune responses to influenza virus infection. In summary, our results demonstrated mPSCs, as one of the target cells for influenza A viruses, could modulate early proinflammatory responses to influenza virus infection.

Influenza a virus-triggered autophagy decreases the pluripotency of human-induced pluripotent stem cells

Maternal influenza infection during pregnancy was reported multiple times as the possible cause of many defects and congenital anomalies. Apart from several cases of influenza-related miscarriage during various trimesters of pregnancy, some epidemiological data suggest a link between maternal influenza infection and genetic abnormalities in offspring. However, there are no reports yet describing how maternal influenza alters cellular pathways at early stages of development to result in congenital defects in the fetus. In the present study, using proteomic approaches, we utilized human-induced pluripotent stem cells (hiPSCs) for modeling intrablastocyst infection with influenza virus to not only investigate the vulnerability and responses of pluripotent stem cells to this virus but also to determine the possible impacts of influenza on pluripotency and signaling pathways controlling differentiation and embryogenesis. Our data indicated viral protein production in influenza A virus (IAV)-infected hiPSCs. However, viral replication was restricted in these cells, but cell viability and pluripotency were negatively affected. These events occurred simultaneously with an excessive level of IAV-induced autophagy as well as cytopathic effects. Quantitative SOMAscan screening also indicated that changes in the proteome of hiPSCs corresponded to abnormal differentiation in these cells. Taken together, our results showed that IAV-modulated reduction in hiPSC pluripotency is associated with significant activation of autophagy. Further investigations are required to explore the role of IAV-induced autophagy in leading pluripotent stem cells toward abnormal differentiation and impaired development in early stages of embryogenesis.

Development and characterization of swine primary respiratory epithelial cells and their susceptibility to infection by four influenza virus types

Influenza viruses are a group of respiratory pathogens that have evolved into four different types: A, B, C, and D. A common feature is that all four types are capable of replicating and transmitting among pigs. Here, we describe the development of isogenous cell culture system from the swine respiratory tract to study influenza viruses. Phenotypic characterization of swine primary nasal turbinate, trachea and lung cells revealed high expression of cytokeratin and demonstrated tissue site dependent expression of tight junction proteins. Furthermore, lectin binding assay on these cells demonstrated higher levels of Sia2-6Gal than Sia2-3Gal receptors and supported the replication of influenza A, B, C, and D viruses to appreciable levels at both 33 and 37 °C, but replication competence was dependent on virus type or temperature used. Overall, these swine primary respiratory cells showed epithelial phenotype, which is suitable for studying the comparative biology and pathobiology of influenza viruses.

Tissue tropisms opt for transmissible reassortants during avian and swine influenza A virus co-infection in swine

Genetic reassortment between influenza A viruses (IAVs) facilitate emergence of pandemic strains, and swine are proposed as a "mixing vessel" for generating reassortants of avian and mammalian IAVs that could be of risk to mammals, including humans. However, how a transmissible reassortant emerges in swine are not well understood. Genomic analyses of 571 isolates recovered from nasal wash samples and respiratory tract tissues of a group of co-housed pigs (influenza-seronegative, avian H1N1 IAV-infected, and swine H3N2 IAV-infected pigs) identified 30 distinct genotypes of reassortants. Viruses recovered from lower respiratory tract tissues had the largest genomic diversity, and those recovered from turbinates and nasal wash fluids had the least. Reassortants from lower respiratory tracts had the largest variations in growth kinetics in respiratory tract epithelial cells, and the cold temperature in swine nasal cells seemed to select the type of reassortant viruses shed by the pigs. One reassortant in nasal wash samples was consistently identified in upper, middle, and lower respiratory tract tissues, and it was confirmed to be transmitted efficiently between pigs. Study findings suggest that, during mixed infections of avian and swine IAVs, genetic reassortments are likely to occur in the lower respiratory track, and tissue tropism is an important factor selecting for a transmissible reassortant.

Comparison of Porcine Airway and Intestinal Epithelial Cell Lines for the Susceptibility and Expression of Pattern Recognition Receptors upon Influenza Virus Infection

Influenza viruses infect the epithelial cells of the swine respiratory tract. Cell lines derived from the respiratory tract of pigs could serve as an excellent in vitro model for studying the pathogenesis of influenza viruses. In this study, we examined the replication of influenza viruses in the MK1-OSU cell line, which was clonally derived from pig airway epithelium. MK1-OSU cells expressed both cytokeratin and vimentin proteins and displayed several sugar moieties on the cell membrane. These cells also expressed both Sial2-3Gal and Sial2-6Gal receptors and were susceptible to swine influenza A, but not to human B and C viruses. Interestingly, these cells were also permissive to infection by influenza D virus that utilized 9-O-acetylated glycans. To study the differences in the expression of pattern recognition receptors (PRRs) upon influenza virus infection in the respiratory and digestive tract, we compared the protein expression of various PRRs in MK1-OSU cells with that in the SD-PJEC cell line, a clonally derived cell line from the porcine jejunal epithelium. Toll-like receptor 7 (TLR-7) and melanoma differentiation-associated protein 5 (MDA5) receptors showed decreased expression in influenza A infected MK1-OSU cells, while only TLR-7 expression decreased in SD-PJEC cells. Further research is warranted to study the mechanism behind the virus-mediated suppression of these proteins. Overall, this study shows that the porcine respiratory epithelial cell line, MK1-OSU, could serve as an in-vitro model for studying the pathogenesis and innate immune responses to porcine influenza viruses.

[Expressions of OCT4, Notch1 and DLL4 and their clinical implications in epithelial ovarian cancer]

OBJECTIVE

To investigate the correlations among OCT4, Notch1 and DLL4 and their association with the clinicopathological features of patients with epithelial ovarian cancer (EOC).

METHODS

A total of 207 specimens of EOC and 65 specimens of benign ovarian epithelial tumor tissues were examined for expressions of OCT4, Notch1 and DLL4 proteins using immunohistochemistry.

RESULTS

The positivity rates of OCT4, Notch1 and DLL4 in EOC tissues were 60.0%, 61.8% and 60.9%, respectively, significantly higher than the rates in benign epithelial tumor tissues (9.2%, 6.2%, and 0, respectively; P<0.05). The expressions of OCT4, Notch1 and DLL4 in EOC were significantly correlated with tumor differentiation, FIGO stage, and lymph node metastasis (P<0.05). DLL4 was positively correlated with OCT4 and Notch1 expressions (r=0.758 and 0.704, respectively, P<0.001), and the latter two were also positively correlated (r=0.645, P<0.001). Overexpressions of OCT4, Notch1 and DLL4 were associated with a poor prognosis, and the survival rate was significantly lower in patients positive for OCT4, Notch1, and DLL4 than in the negative patients (P<0.05). FIGO stage and expressions of OCT4 and DLL4 were independent prognostic factors of EOC (P<0.05).

CONCLUSION

The expressions of OCT4, Notch1 and DLL4 are correlated with the differentiation, lymph node metastasis, clinical stage and prognosis of EOC. Combined detection of the 3 proteins has an important value in predicting the progression and prognosis of EOC.

[Expressions of OCT4, Notch1 and DLL4 and their clinical implications in epithelial ovarian cancer]

OBJECTIVE

To investigate the correlations among OCT4, Notch1 and DLL4 and their association with the clinicopathological features of patients with epithelial ovarian cancer (EOC).

METHODS

A total of 207 specimens of EOC and 65 specimens of benign ovarian epithelial tumor tissues were examined for expressions of OCT4, Notch1 and DLL4 proteins using immunohistochemistry.

RESULTS

The positivity rates of OCT4, Notch1 and DLL4 in EOC tissues were 60.0%, 61.8% and 60.9%, respectively, significantly higher than the rates in benign epithelial tumor tissues (9.2%, 6.2%, and 0, respectively; P<0.05). The expressions of OCT4, Notch1 and DLL4 in EOC were significantly correlated with tumor differentiation, FIGO stage, and lymph node metastasis (P<0.05). DLL4 was positively correlated with OCT4 and Notch1 expressions (r=0.758 and 0.704, respectively, P<0.001), and the latter two were also positively correlated (r=0.645, P<0.001). Overexpressions of OCT4, Notch1 and DLL4 were associated with a poor prognosis, and the survival rate was significantly lower in patients positive for OCT4, Notch1, and DLL4 than in the negative patients (P<0.05). FIGO stage and expressions of OCT4 and DLL4 were independent prognostic factors of EOC (P<0.05).

CONCLUSION

The expressions of OCT4, Notch1 and DLL4 are correlated with the differentiation, lymph node metastasis, clinical stage and prognosis of EOC. Combined detection of the 3 proteins has an important value in predicting the progression and prognosis of EOC.

Replication of influenza A virus in swine umbilical cord epithelial stem-like cells

In this study, we describe the isolation and characterization of epithelial stem-like cells from the swine umbilical cord and their susceptibility to influenza virus infection. Swine umbilical cord epithelial stem cells (SUCECs) expressed stem cell and pluripotency associated markers such as SSEA-1, SSEA-4, TRA 1-60 and TRA 1-81 and Oct4. Morphologically, cells displayed polygonal morphology and were found to express epithelial markers; pancytokeratin, cytokeratin-18 and occludin; mesenchymal cell markers CD44, CD90 and haematopoietic cell marker CD45 were not detected on these cells. The cells had extensive proliferation and self- renewal properties. The cells also possessed immunomodulatory activity and inhibited the proliferation of T cells. Also, higher levels of anti-inflammatory cytokine IL-10 were detected in SUCEC-T cell co-cultures. The cells were multipotent and differentiated into lung epithelial cells when cultured in epithelial differentiation media. We also examined if SUCECs are susceptible to infection with influenza virus. SUCECs expressed sialic acid receptors, used by influenza virus for binding to cells. The 2009 pandemic influenza virus and swine influenza virus replicated in these cells. SUCECs due to their differentiation and immunoregulatory properties will be useful as cellular therapy in a pig model for human diseases. Additionally, our data indicate that influenza virus can infect SUCECs and may transmit influenza virus from mother to fetus through umbilical cord and transplantation of influenza virus-infected stem cells may transmit infection to recipients. Therefore, we propose that umbilical cord cells, in addition to other agents, should also be tested for influenza virus before cryopreservation for future use as a cell therapy for disease conditions.

Porcine lung mesenchymal stromal cells possess differentiation and immunoregulatory properties

Introduction

Mesenchymal stem (stromal) cells (MSCs) possess self-renewal, differentiation and immunoregulatory properties, and therefore are being evaluated as cellular therapy for inflammatory and autoimmune diseases, and for tissue repair. MSCs isolated from bone marrow are extensively studied. Besides bone marrow, MSCs have been identified in almost all organs of the body including the lungs. Lung-derived MSCs may be more effective as therapy for lung diseases as compared to bone marrow-derived MSCs. Pigs are similar to humans in anatomy, physiology and immunological responses, and thus may serve as a useful large animal preclinical model to study potential cellular therapy for human diseases.

Methods

We isolated MSCs from the lungs (L-MSCs) of 4–6-week-old germ-free pigs. We determined the self-renewal, proliferation and differentiation potential of L-MSCs. We also examined the mechanisms of immunoregulation by porcine L-MSCs.

Results

MSCs isolated from porcine lungs showed spindle-shaped morphology and proliferated actively in culture. Porcine L-MSCs expressed mesenchymal markers CD29, CD44, CD90 and CD105 and lacked the expression of hematopoietic markers CD34 and CD45. These cells were multipotent and differentiated into adipocytes, osteocytes and epithelial cells. Like human MSCs, L-MSCs possessed immunoregulatory properties and inhibited proliferation of T cells and interferon-γ and tumor necrosis factor-α production by T cells and dendritic cells, respectively, and increased the production of T-helper 2 cytokines interleukin (IL)-4 and IL-13 by T cells. L-MSCs induced the production of prostaglandin E2 (PGE2) in MSC–T cell co-cultures and inhibition of PGE2 significantly restored (not completely) the immune modulatory effects of L-MSCs.

Conclusions

Here, we demonstrate that MSCs can be isolated from porcine lung and that these cells, similar to human lung MSCs, possess in vitro proliferation, differentiation and immunomodulatory functions. Thus, these cells may serve as a model system to evaluate the contribution of lung MSCs in modulating the immune response, interactions with resident epithelial cells and tissue repair in a pig model of human lung diseases.

Lung-derived SSEA-1(+) stem/progenitor cells inhibit allergic airway inflammation in mice

BACKGROUND

Asthma is characterized by chronic airway inflammation and airway hyperresponsiveness (AHR). Little is known about the role of pulmonary stem/progenitor cells (PSCs) in allergic airway inflammation.

METHODS

To identify and investigate the role of PSCs in the bronchial epithelium of neonatal mice, we developed an enzyme-based digestion method to obtain single-cell suspension from lung tissues. Characterization of PSCs was performed using flow cytometry, real-time PCR, immunofluorescence staining, confocal microscopy, and scanning electron microscopy. The effects of SSEA-1(+) (stage-specific embryonic antigen-1) PSCs was studied in an in vivo model of ovalbumin-induced allergic inflammation and an in vitro model of cell-based regulation using flow cytometry, real-time PCR, and immune-blotting.

RESULTS

Single-cell suspensions derived from neonatal lung tissue included populations that expressed either SSEA-1(+) or Sca-1(+) (stem cell antigen-1). The SSEA-1(+) PSCs were highly prevalent in neonatal mice, and they were rare in adult mice. Enriched neonatal SSEA-1(+) PSCs had the ability of self-renewal and differentiated into pneumocytes and tracheal epithelial cells. SSEA-1(+) PSCs reduced AHR and airway damage in asthmatic mice by decreasing eosinophil infiltration, inhibiting chemokines/cytokines production, and preserving the level of CCSP.

CONCLUSIONS

Here, we demonstrated that neonatal SSEA-1(+) PSCs play an immunomodulatory role in the progression of asthma by reducing lung damage and inhibiting inflammatory responses. Further understanding the molecular mechanisms of neonatal SSEA-1(+) PSCs might shed light on exploring the novel therapeutic approaches for allergic airway inflammation.

Adverse effects of Influenza A(H1N1)pdm09 virus infection on growth performance of Norwegian pigs - a longitudinal study at a boar testing station

BACKGROUND

Influenza A(H1N1)pdm09 virus infection in Norwegian pigs was largely subclinical. This study tested the hypothesis that the infection causes negligible impact on pigs' growth performance in terms of feed conversion efficiency, daily feed intake, daily growth, age on reaching 100 kg bodyweight and overall feed intake. A sample of 1955 pigs originating from 43 breeding herds was classified into five infection status groups; seronegative pigs (n = 887); seropositive pigs (n = 874); pigs positive for virus at bodyweight between 33 kg and 60 kg (n = 123); pigs positive for virus at bodyweight between 61 kg and 80 kg (n = 34) and pigs positive for virus at bodyweight between 81 kg and 100 kg (n = 37). Each pig had daily recordings of feed intake and bodyweight from 33 kg to 100 kg. Marginal effects of the virus infection on the outcomes were estimated by multi-level linear regression, which accounted for known fixed effects (breed, birthdate, average daily feed intake and growth phase) and random effects (cluster effects of pig and herd).

RESULTS

The seropositive and virus positive pigs had decreased (P value<0.05) growth performance compared to seronegative pigs even though feed intake was not decreased. Reduced feed conversion efficiency led to lower average daily growth, additional feed requirement and longer time needed to reach the 100 kg bodyweight. The effects were more marked (P value<0.03) in pigs infected at a younger age and lasted a longer period. Despite increased feed intake observed, their growth rates were lower and they took more time to reach 100 kg bodyweight compared to the seronegative pigs.

CONCLUSION

Our study rejected the null hypothesis that the virus infection had negligible adverse effects on growth performance of Norwegian pigs.

Stem cells, cell therapies, and bioengineering in lung biology and diseases. Comprehensive review of the recent literature 2010-2012

A conference, "Stem Cells and Cell Therapies in Lung Biology and Lung Diseases," was held July 25 to 28, 2011 at the University of Vermont to review the current understanding of the role of stem and progenitor cells in lung repair after injury and to review the current status of cell therapy and ex vivo bioengineering approaches for lung diseases. These are rapidly expanding areas of study that provide further insight into and challenge traditional views of mechanisms of lung repair after injury and pathogenesis of several lung diseases. The goals of the conference were to summarize the current state of the field, to discuss and debate current controversies, and to identify future research directions and opportunities for basic and translational research in cell-based therapies for lung diseases. The goal of this article, which accompanies the formal conference report, is to provide a comprehensive review of the published literature in lung regenerative medicine from the last conference report through December 2012.

Strategies for whole lung tissue engineering

Recent work has demonstrated the feasibility of using decellularized lung extracellular matrix scaffolds to support the engineering of functional lung tissue in vitro. Rendered acellular through the use of detergents and other reagents, the scaffolds are mounted in organ-specific bioreactors where cells in the scaffold are provided with nutrients and appropriate mechanical stimuli such as ventilation and perfusion. Though initial studies are encouraging, a great deal remains to be done to advance the field and transition from rodent lungs to whole human tissue engineered lungs. To do so, a variety of hurdles must be overcome. In particular, a reliable source of human-sized scaffolds, as well as a method of terminal sterilization of scaffolds, must be identified. Continued research in lung cell and developmental biology will hopefully help identify the number and types of cells that will be required to regenerate functional lung tissue. Finally, bioreactor designs must be improved in order to provide more precise ventilation stimuli and vascular perfusion in order to avoid injury to or death of the cells cultivated within the scaffold. Ultimately, the success of efforts to engineer a functional lung in vitro will critically depend on the ability to create a fully endothelialized vascular network that provides sufficient barrier function and alveolar-capillary surface area to exchange gas at rates compatible with healthy lung function.